O-Ring No Metal Detectable No X-Ray Detectable System of Measurement Inch Cross Section Shape Round O-Ring Material Buna N Durometer (Hardness) Rating Very Hard Nominal Inside Dia 23 in Nominal Width 3/16 in Actual Inside Dia 22.94 in Actual Width 0.21 in Dash Number 392 Color Black Durometer 90 Shore A Meets/Exceeds ASTM D2000 NBR 90 Nominal Outside Dia 23 3/8 in Actual Outside Dia 23.36 in FDA Approved No